1. Field of Invention
This invention relates generally to pelletized soil enhancing material formed of 1) composted organic waste and sewer sludge, 2) fibrous cellulosic material and 3) herbal and soil enhancing chemicals.
2. Background and Description of Prior Art
The use of organic waste for soil enhancement and plant nutrition has long been known and practiced. The material was originally used largely in its native state, but through its historicity the use became more and more sophisticated until in the present day such materials are often quite highly processed before use to beneficiate them in various fashions and accelerate their reactions. This beneficiation often has provided quantities of nitrogenous materials, phosphates and potassium that are quickly released in soluble, plant assimilable form to such a degree that the sophisticated materials have in themselves become an environmental liability by overloading the soil with soluble plant nutrient materials sufficient to deleteriously change the entire ecosystem. The instant invention seeks to present a solution to this problem by providing such waste materials in a pelletized product that does not provide such a quick release of soluble products, but rather maintains the beneficial products in a less soluble form while providing means for soluble release at a slower rate over a longer period of time to allow assimilation of the materials by the soil and herbage therein to prevent deleterious environmental pollution, especially of the ground water.
Two general types of organic waste that have commonly been used for plant nutrition and soil enhancement, because of the availability of substantial amounts of such materials and the difficulty of their disposition in other fashions, are sewage sludge, especially that containing a substantial portion of animal excrement, and fibrous cellulosic waste, especially as derived from agricultural and arboreal wastes. In the past, each of these materials has tended to have been individually used, probably because of the particular and different processing requirements for each, but in distinction the instant product uses both materials in combination to provide synergistic benefits.
Fibrous cellulosic materials if used alone for soil beneficiation will tend to increase tilth, but at the expense of the available nitrogen content of the soil as nitrogen is required for microbal metabolic processes that cause degradation of the cellulosic material and this nitrogen must come from the available nitrogenous component of the surrounding soil. This problem has sometimes been addressed by acidifying the cellulosic material to encourage the development of humic acids to aid the cellulosic degradation process, but this solution generally has only shortened the degradation period and has not lessened the need for nor provided the nitrogenous material required for degradation. Nitrogen fixing microorganisims have been added to the cellulosic material, but this again has had substantially the same affect as acidification and largely has only exacerbated the problem without much, if any, acceleration of the process.
Another response to the problem of nitrogen depletion resulting from cellulosic degradation has been to provide additional nitrogenous material in the form of soluble nitrates, but this response has tended to provide an excess of soluble nitrates such that the nitrates are not assimilated and tend to leach into ground water to provide general environmental contamination. The instant product does not provide a substantial excess of soluble nitrogenous material nor does it abnormally acidify the cellulosic material, but rather it allows the decomposition process to proceed at a normal slower rate while providing means for supplying nitrogenous material and microbally generated humic acids as required over the disintegration period. The retention of the more natural process of forming humate maintains the plant nutrient material in humic acid molecules that are absorbed into associated organic colloids to form molecular clusters of humic acids and humic salts with the plant nutrients to provide a stable and efficient release of usable amounts of nutrients throughout the decomposition process.
Most sewer sludge, when removed from treatment facilities using common modern treatment processes, contains substantial quantities of viable microbes, principally of a bacterial nature, and often other viable biological material of a reproducible nature that may be deleterious to the environment, especially such as small seeds, plant parts, molds, yeasts and the like. In the early use of such material, it generally was applied upon land in its native state, either in a fluidic form or as a dried, particulate solid, with its viable biologic components still substantially in place.
As problems created by the viable biologic components came to be better realized, the sludge responsively was further processed to destroy the viability of some biologic components, generally by composting, oxidative aeration, thermal treatment, or combinations of these processes. This further processing has increased cost, however, and has been somewhat limited by reason of its economic viability. In general such further processing has not been designed to deal selectively or differentially with various of the biologically viable components in the sludge. The instant invention in contradistinction further processes sewer sludge in an economically viable manner by admixing it with cellulosic waste material and composting the mixture to institute humification that naturally destroys much or substantially all of the deleterious biological material while not affecting the viability of the beneficial soil microbes. The humification is only partially accomplished while maintaining soil nutrients in complex organic forms that are not readily soluble without further acidification by plant roots or further humification.
In general most pathologic bacteria are mesophyllic and are destroyed in a temperature range between 130 to 160 degrees F., while nonpathologic bacteria generally are thermophilic and will survive and retain viability in the mesophyllic range. Since the composting reaction is exothermal, the admixed sludge and cellulosic material are maintained for at least a portion of their composting period in the thermophilic range to destroy most, if not substantially all, of the pathogenic microbes. This composting process may be continued with sequential temperature changes for substantial periods of time to allow partial humification of the cellulosic material and this has the secondary benefit of destroying at least substantial portions, if not all, of any contained viable botanical and non-microbal material.
The resultant partially humified mixture is then admixed with additional cellulosic material and desired chemical additives and pelletized through a mill type die that has tapered openings which again provides an exothermal pelletizing process. This pelletizing process is regulated to attain temperatures in the pelletized product in the thermophilic range of approximately 180 degrees F. which, together with the pressures involved, tend to destroy any remaining pathogenic bacteria that might still be in the material, while yet creating a configurationally sustaining pellet of substantial durability that yet will properly disintegrate in use.
Pellets formed by the instant process continue the humification after placement and maintain portions of the nutrient materials in complex, organic molecules for timed release upon further acidification so as not to pollute the soil environment with an excess of readily soluble nutrient materials. The pellets also contain cellulosic material to provide soil humus, and provide enough nitrogen to further the humification process without removing substantial quantities of nitrogen from the surrounding soil environment. The pelletized material does not have significant levels of pathogenic microbes, but yet provides substantial quantities of viable soil bacteria to establish or reinforce the microbal population in the area of use to further aid future humification. The odors commonly associated with sewer sludge are not present in the pelletized product as those odors generally are created by mesophyllic bacteria which are not present.
Our invention resides not in any one of these features individually, but rather in the synergistic combination of all of its features that necessarily give rise to the product and process flowing therefrom.